Porphysome nanoparticles for enhanced photothermal therapy in a patient-derived orthotopic pancreas xenograft cancer model: a pilot study.

Local disease control is a major challenge in pancreatic cancer treatment, because surgical resection of the primary tumor is only possible in a minority of patients and radiotherapy cannot be delivered in curative doses. Despite the promise of photothermal therapy (PTT) for focal ablation of pancreatic tumors, this approach remains underinvestigated. Using photothermal sensitizers in combination with laser light irradiation for PTT can result in more efficient conversion of light energy to heat and improved spatial confinement of thermal destruction to the tumor. Porphysomes are self-assembled nanoparticles composed mainly of pyropheophorbide-conjugated phospholipids, enabling the packing of ∼80,000 porphyrin photosensitizers per particle. The high-density porphyrin loading imparts enhanced photonic properties and enables high-payload tumor delivery. A patient-derived orthotopic pancreas xenograft model was used to evaluate the feasibility of porphysome-enhanced PTT for pancreatic cancer. Biodistribution and tumor accumulation were evaluated using fluorescence intensity measurements from homogenized tissues and imaging of excised organs. Tumor surface temperature was recorded using IR optical imaging during light irradiation to monitor treatment progress. Histological analyses were conducted to determine the extent of PTT thermal damage. These studies may provide insight into the influence of heat-sink effect on thermal therapy dosimetry for well-perfused pancreatic tumors.